A new transition method of square wave-direct voltage signal

The difficulty for applocation of CCD(charge coupled devices) in control circuit(how to transform square wave to direct voltage) is discussed and analyzed.Two kind of transformation methods are introduced at first and the advantages and disadvantages of the two kind methods are analyzed and compared too. A neoteric transformation method is brought forward at last:That is themethod of transforming square wave to direct voltage signal based on filter thought.The result of this method is stable and reliable through test and experiment.